My customer needs to have backup lines for their branch offices. They have installed on each branch office a router (RV042 or TL ER6120 or ASA5505), on each branch office are installed 2 fiber optic transceiver from diferent ISPs. At headquarter they have installed a cisco 892FSP. 892 WAN1 interface is connected to a layer 3 switch (on that switch are connected many Patch cords connected to many ONTs), WAN2 is connected to a catalyst 2960 switch with a SFP connected. Customer needs to have backup link between headquarter and branch offices. Can anyone help?